Replace batteries in electric toothbrushes

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We use two Braun Oral-B electric toothbrushes. Both use a NiMh rechargeable battery that looses its capacity over time. One of the toothbrushes even shut down completely during its use, even when it was charged more than 24h before. So I started to check what must be done to replace the battery.


I’ve found two detailed instructions for both our toothbrushes. The one is for a Braun Oral-B Professional Care 500 (Type 4729) and the other is a Braun Oral-B Professional Care Type 3754 & 3756. You can find the exact type number on the bottom of the toothbrush.


You’ll need:

  • a soldering iron
  • lead free solder
  • a desoldering pump - You’ll need to desolder the batteries as well as the motors
  • desoldering braid - helps a lot when the desoldering pump did not get everything and connectors are still stuck
  • Wirecutter - to shorten the connectors from your replacement battery
  • a replacement batterie - search for the type number in combination with replacement batterie on a web shop of your choice


The complete replacement of two toothbrush batteries was done in a single evening and took me two hours. Its not that complicated and spares you unnecessary electro waste. Its also a good chance to see the insides of these little machines and how they are recharged. Pretty interesting engineering. Too bad its

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